help: electrical problems, 93 Saturn SL2

Most of the time it runs fine.

If she leaves the rear defroster on and turns the key off, the battery goes
dead.

Sometimes, after the car starts normally, the aftermarket CD player/radio
blinks on/off, the lights and gauges dim or go out, and after she turns the
key off, the battery is dead.

I recharge the battery and it ususally starts and runs fine. For a while.

Q's:

1. Any immediate diagnoses or quick fixes?
2. Is this something that can be diagnosed with a fancy scanner or computer
or electrrical gizmo?

As always, thanks a heap,
-jbb

 

First thing a technician looks for is "Previous Work"... Who ever
installed the aftermarket radio has very likely screwed something up.

 

Are the metal portions of the body/chassis starting to rust? The
problems you describe can happen when there are bad ground
connections. Use a meter to check for a voltage drop from battery
minus terminal to engine block to various points on the body with the
engine and accessories running. I would be concerned with any
readings over .2 volt.

Also an excessive voltage drop from the alternator to battery will
prevent the battery from charging as it should.

I had this happen on a car that was rusting out. Dashboard lights
would flicker, battery liked to go dead, etc. Fixed it by running
extra ground wires from the battery to engine to alternator frame to
various points on the body. Worked fine after that.

Good luck,
Jim

 

Alternator ?